Introduce Me....

So i've been hearing alot about Diablo 3, and i have seen game-play vids. Yet i dont really know what it is.
could anyone introduce to me:

The general lore of diablo. ( no need to write pages, just short)
The idea of Diablo. whats the goal in the game?
Is it an MMO - solo RPG?
Please explain me further how the gameplay is. the vids on Utube wasn't very usefull.

Think a RTS but with only 1 character you control. You level up as an mmo and get skills and have talent trees. You can either play alone (pretty boring imo) or connect via battle.net to play with others, think like the LFG system in wow.

The goal is to defeat Diablo and complete the missions/quests, but you dont have to. Its basicly a much darker and gorier WoW that you look in bird perspectiv + click with the mouse to move forward.

The lore? Well read on the official diablo 3 page and read up, or diablo wiki.

Lore: the universe is torn by eternal war between Heaven and Hell. Ages ago, a demoness Lilith and angel Inarius decided to retire from war and created a world, called Sanctuary, shielded from direct influence of both Heaven and Hell. Children of Lilith and Inarius were actual humans, who had potential to be more powerful than Demons and Angels. To prevent that, a special artifact called Worldstone was created in order to both shield the Sanctuary and diminish the power of humans. Shielded as it was, Sanctuary was still susceptible to corruption of Hell and corrupted humans could actuallylah call forth essence of Prime Evils - Mephisto, Lord of Hatred, Baal, Lord of Destruction and Diablo, Lord of Terror - into Sanctuary. Blah-blah-blah, long story short, Prime Evils were defeated (Diablo was even defeated twice), but Worldstone was corrupted from within and Archangel Tyrael (one of the most kickasss amongst angels) destroyed the Worldstone, lifting limits from humanity's powers and destroying the barrier that didn't allow Angles and Demons enter Sanctuary directly. At this happy moment Diablo III kicks in...
Playable heroes are always humans, proving supremacy of human race over minions of Burning Hells (and possibly even those of Heaven in Diablo III)

Goal of the game is to be beat crap out of Diablo, but that doesn't really end the game (in Diablo II at least) - you can continue to farm monsters and bosses (they respawn) and get better and better gear. Bur lore-wise you just have to kill Diablo or whatever end boss there may be.

Atmosphere - nowhere as happy as that of WoW. WoW is humoristic fantasy, after all, Diablo is more serious gothic fantasy. You really feel like a powerful hero, a chosen one, fighting a desperate battle against all impossible odds and winning it. Tremendous game.